Device for condensing metal vapours



Sept. 21, 1965 P. w. GIBBS DEVICE FOR CONDENSING METAL VAPOURS 2 Sheets-Sheet 1 Filed Feb. 17, 1961 ZJ MAV PATENT AGENT Sept. 21, 1965 P. w. GIBBS 3,207,495

DEVICE FOR CONDENSING METAL VAPOURS Filed Feb. 1'7, 1961 2. Sheets-Sheet 2 PATENT AGENT United States Patent 3,207,495 DEVICE FOR CONDENSING METAL VAPOURS Peter W. Gibbs, Codben, Ontario, Canada, assignor to Dominion Magnesium Limited, Toronto, Ontario, Canada, a corporation of Canada Filed Feb. 17, 1961, Ser. No. 90,091 3 Claims. (Cl. 26619) This invention relates to a device for increasing the condensing capacity of condensers employed to collect metal vapours in solid form. It is particularly concerned with the thermal reduction and distillation of metals from their ores but is applicable to the purification of metals by distillation techniques.

Alkaline earth metals are extracted from their ores by heating with a reducing agent in a reaction zone controlled atmospheric and pressure conditions, withdrawing the metal as vapour and collecting it in an adjoining cooled condenser. In the purification of metals by distillation, the vapourized metals also require condensation.

The objects of the present invention are to permit the metal vapour condenser to handle larger volumes of metal and still be able to facilitate widely and rapidly varying distillation rates without altering the size of the condenser and the amount of external cooling employed in connection with known thermal reduction processes. It is a further object to accomlish these objectives and still maintain the condenser temperature sufliciently warm to avoid formation of pyrophoric or lowgrade condensates and insure direct path of contact between the condenser and the external cooling means.

In the attached drawings,

FIGURE 1 is a cross sectional longitudinal view of the condenser device shown in direct attachment to a retort,

FIGURE 2 is a cross sectional view on line 22 of FIGURE 1,

FIGURE 3 is a cross section on line 33 of FIGURE 1 showing a heat radiation shield between the condenser and the reaction chamber,

FIGURE 4 is an end view of the radiation shield of an alternate form of the radiation shield, and

FIGURE 5 is a longitudinal cross section taken on line 55 of FIGURE 4.

In FIGURE 1 the annular condenser 1 is shown as constituting an extension of the reaction chamber of a metal retort 2. It may be a separate unit to be secured to the reaction chamber in which reduction or purification takes place. 3 is an opening to permit reduction of pressure within the condenser and reaction chamber by a vacuum pump or the like. Surrounding the outer end section of the condenser is a water jacket 4 through which cooling water is circulated and 5 is a sealing cover for the outer end of the condenser with a gasket therein.

Within the condenser is located a removable annular metal sleeve 6 the inner end and lower outer end of which are in direct point contact with the condenser wall, thus leaving an annular space between the sleeve and condenser wall. Within the outer end of the sleeve is a baffle 8 which prevents escape of metal vapour. In the lower wall of the sleeve adjacent to the baflle is a plurality of openings 9. Five such openings of 1 inch diameter, located at 2 /2 inch centers are shown. The number, shape, size and disposition of the openings may be varied. Openings 2" in diameter and as many as 9 of 1 inch diameter have been used. Their location will depend on the characteristics of the metal being condensed with most effective local cooling and ease of removal being obtained when vents are situated to permit the shortest possible cooling path. The vents can be located at any point around the periphery and along the length of the condenser sleeve to insure close control of the cooling 3,207,495 Patented Sept. 21, 1965 of the condensate; the particular location being dependent upon the temperature conditions within the condenser. Also by means of suitable spacers the condenser sleeve can be positioned concentric within the condenser chamber and vents located at equal intervals around the circumference of the sleeve.

In practice, using the heretofore known condenser arrangement because of increased distillation rates it was found that the condenser capacity was taxed to the limit with occasions being encountered where because of some uncontrollable condition the rate of heat transfer was insufficient to maintain the temperature within the condenser below the melting point of the metal being condensed. When such occurred a portion of the liquid collecting in the condenser feeds back by gravity into the reaction zone and is revaporized. This further overloads the condensing requirements of the condenser and causes a continuous refluxing condition with excessive temperatures being reached both in the reaction chamber and the condenser which has deleterious effects on their service life. Such condensates on discharging are usually a total loss as well as a hazard in operation. Also some of the liquid metal formed in these instances flows in the space between the sleeve and the condenser zone wall where it freezes making the removal of the condenser sleeve on discharging very difficult and costly.

The openings or vents in the condenser sleeve, as above described, provide direct cooling links of metal between the metal of the removable sleeve and the cooled wall of the condenser. This increases the area of direct contact between the condensate and the cooling surface of the condenser and the thermal conductivity of the metal being condensed being higher than that of the steel of the sleeve further increases the cooling efficiency of the condenser device. The metal links extending through the vents, are readily broken when removing the loaded sleeve from the condenser by raising the cold end of the sleeve with a pry or the like. An increase in condensing capacity up to 114 percent of the original capacity was required by other improvements but not possible without the hazards and losses due to refluxing or burnt crowns until the vented condensers were installed. The incidence of hot condensates was previously a complete bar or limiting factor to further improvements in metal production rates but with this improvement it has been shown on individual tests that condensates of 157 percent of the original capacity can be safely handled.

To further illustrate the benefit of these metal links formed through the vents in the sleeve the following explanation is given.

The condensed metal vapours form in the sleeve what is called a crown of a shape as roughly indicated in FIGURE 1 and numbered 10. When the rate of cooling in the condenser is not equated with the rate of vapour formation the crown becomes too hot and redistillation of the metal occurs as previously described. In previous practice hot crowns have appeared too frequently with the consequent reduction in production efliciency. These cooling metal links provide ample cooling to cope with rapid surges in distillation rates that may be encountered, but at the same time permit the temperature of the condenser to be sufliciently warm during a period of low condensing rate, so as not to form a pyrophoric or low grade condensate. Also it has been found that because of the more eflicient use of the external cooling, the amount of such cooling can be reduced which results in less heat drag from the adjoining reaction zone and an improvement in thermal reduction efiiciency. The battle 8 in the sleeve is in the form of a reinforced cylindrical box having an opening in its outer end for removal purposes.

The heat radiation shield shown in FIGURES 1 and 3 opening 12 therein and a smaller disk 13 anchored to disk 11 by radial fins 14, for the purpose of retarding heat radiation flow to the condenser.

In the form illustrated in FIGURES 4 and 5 the shield is in the form of a cylindrical box 15 having a tapered side wall 16, and a central channel opening 17 surrounded by insulating material.

What is claimed is:

1. A condenser apparatus for solidifying metal vapor produced from ores by thermal reduction comprising a housing having a closed end and an open end attachable to a thermal reduction furnace, a removable, open metal sleeve member disposed in said housing, a removable baflle member disposed in said sleeve member adjacent an end thereof furthest removed from said furnace and said sleeve member having at least one opening therein disposed substantially adjacent said baflle member and between said baflie member and the open end of said sleeve member nearest said furnace.

2. A condenser apparatus according to claim 1 wherein there is provided a cooling jacket surrounding the housing being axially positioned relative to said sleeve member at the location of said opening in said sleeve member.

3'. A condenser apparatus according to claim 1, having 4. a heat radiation shield disposed adjacent the end thereof attachable to said thermal reduction furnace.

References Cited by the Examiner UNITED STATES PATENTS 1,594,348 8/26 Bakken 266 1,727,179 9/29 Rostek 165154 2,426,148 8/ 47 Hybinette et a1 26615 2,814,477 11/57 Loomis et al. 26615 2,837,328 6/58 Pidgeon 266-15 FOREIGN PATENTS 86,913 1/ Switzerland. 254,591 12/48 Switzerland. 8,898 6/ 49 Switzerland. 25 8,900 6/ 49 Switzerland.

OTHER REFERENCES Pidgeon et al.: Thermal Production of Magnesium; Am. Inst. of M. & M. E., 1944, vol. 159, pp. 318, 319, and 369.

MORRIS O. WOLK, Primary Examiner.

HERBERT L. MARTIN, Examiner. 

1. A CONDENSER APPARATUS FOR SOLIDIFYING METAL VAPOR PRODUCED FROM ORES BY THERMAL REDUCTION COMPRISING A 